1. Field of the Invention
This invention relates generally to hand tools, and is concerned in particular with hammers and the like having internally reinforced jacketed handles.
2. Description of the Prior Art
It has long since been known to manufacture hammers, hatchets and the like with steel handles. Such tools are disclosed, for example in U.S. Pat. Nos. 1,598,279 (Hobbs); 1,707,787 (Estwing); 2,884,969 (Lay); 3,208,724 (Vaughan); 3,320,985 (Maguire); and 4,154,273 (Pollak). While steel handles offer increased bend strength and resistance to failure, these advantages are to some extent offset by the injuries that can result in the event that the handles strike a user's hand or fingers, or come into contact with exposed electrical wiring at a construction site.
These problems have been alleviated by other so-called "jacketed" designs, where the metallic handle components are encased in softer dielectric materials, e.g., acetate, polyethylene, fiberglass and the like. Examples of these jacketed designs are shown in U.S. Pat. Nos. 2,837,381 (Sarlandt); 3,779,296 (Echeverria); and 4,738,166 (Yamaguchi).
In the prior art jacketed designs, metal-to-metal contact between coacting components provides the primary means for securing the striking heads to the handles. More particularly, in the patent to Yamaguchi, the metallic head is secured directly to the metallic reinforcing tube, presumably by force-fitting. In the Sarlandt patent, the metallic striking head is connected to what appears to be a metallic reinforcing element by means of a pin which again is presumably metallic, whereas in the patent to Echeverria, a metal wedge is forced into the upper end of the tubular metallic reinforcing element to expand the surrounding jacket against the interior of an eye extending through the striking head.
In each of these designs, the reliance on metal-to-metal contact raises the risk of the striking heads loosening under the repeated shocks and stresses accompanying normal usage.